Patent application title: ARTIFICIAL TURF

Abstract:

An artificial turf has a base layer and a multiplicity of blades fixed to
and projecting upward from the base layer. Each of the blades is formed
of an elongated plastic filament having a longitudinally extending inner
part of plastic and a longitudinally extending outer part bonded to the
inner part and of a plastic different from the inner-part plastic. Both
parts extend the full length of the respective blade.

Claims:

1. An artificial turf comprising:a base layer; anda multiplicity of blades
fixed to and projecting upward from the base layer, each of the blades
being formed of an elongated plastic filament having a longitudinally
extending inner part of plastic and a longitudinally extending outer part
bonded to the inner part and of a plastic different from the inner-part
plastic, both parts extending generally a full length of the respective
blade.

2. The artificial turf defined in claim 1 wherein the outer part is
tubular and surrounds the inner part.

3. The artificial turf defined in claim 2 wherein the outer part is a
polyolefin.

4. The artificial turf defined in claim 3 wherein the outer part is
polyethylene.

5. The artificial turf defined in claim 4 wherein the outer part is linear
low-density polyethylene.

6. The artificial turf defined in claim 2 wherein the inner part is
polyamide or polyester.

8. The artificial turf defined in claim 2 wherein each part further
comprises a tubular intermediate part surrounding the inner part,
surrounded by the outer part, and of a plastic different from the
plastics of at least one of the inner and outer parts.

9. The artificial turf defined in claim 8 wherein the inner part, the
intermediate part, and the outer part all extend generally full lengths
of the filament.

10. The artificial turf defined in claim 8 wherein the intermediate layer
is formed of a polyamide/polyolefin copolymer or a polyolefin modified
with maleic acid derivative.

12. The artificial turf defined in claim 8 wherein the outer part has a
cross-sectional area equal to between 5% and 50% of a total
cross-sectional area of the blade.

13. The artificial turf defined in claim 8 wherein the outer part has a
cross-sectional area equal to between 10% and 40% of a total
cross-sectional area of the blade.

14. The artificial turf defined in claim 8 wherein the intermediate part
has a cross-sectional area equal to between 3% and 20% of a total
cross-sectional area of the blade.

15. The artificial turf defined in claim 8 wherein the intermediate part
has a cross-sectional area equal to between 5% and 15% of a total
cross-sectional area of the blade.

16. The artificial turf defined in claim 8 wherein the outer part has a
cross-sectional area equal to between 30% and 93% of a total
cross-sectional area of the blade.

17. The artificial turf defined in claim 8 wherein the outer part has a
cross-sectional area equal to between 35% and 80% of a total
cross-sectional area of the blade.

18. The artificial turf defined in claim 1 wherein the inner part is
formed with at least one longitudinally extending void.

Description:

FIELD OF THE INVENTION

[0001]The present invention relates to artificial turf.

BACKGROUND OF THE INVENTION

[0002]Standard to artificial turf, in particular for sports fields and
lawns typically has blades made of plastic, normally mixtures of plastic,
with mixtures of plastic in particular being used. The artificial turf
should meet as many requirements as possible. First, the artificial turf
should not cause any injury or discomfort to the skin upon intensive
contact with human skin, for example, when athletes fall and slide on it.
Moreover, it is desirable for the blades to return to their original
position as completely as possible after impact by the users, in
particular after the artificial turf has been walked on repeatedly.
Furthermore, the artificial turf should also provide sufficient cushion,
that is be soft like real grass.

[0003]The artificial turfs known up to now have the disadvantage that they
normally do not meet all of the requirements mentioned above very well.
Up to now, when a known artificial turf is designed such that the blades
return to their erect position in a problem-free fashion after repeatedly
being bent over, this feature is traded off against gentleness of the
artificial turf on skin. In other words, intensive rubbing of human skin
on this artificial turf may result in injury, so-called rug burns. On the
other hand, if the artificial turf is designed with an eye to gentleness
on the skin, it normally easily crushable, that is the blades to not
stand up again once bent over, in other words the turf is readily
flattened out. The cushioning ability achieved in the known types of
artificial turf also leaves much to be desired. As a result, the known
types of artificial turf normally do not meet all of the above
requirements and therefore require improvement.

OBJECTS OF THE INVENTION

[0004]It is therefore an object of the present invention to provide an
improved artificial turf.

[0005]Another object is the provision of such an improved artificial turf
that overcomes the above-given disadvantages, in particular that has in
particular an optimal degree of gentleness on the skin and where
nonetheless the blades are able to return to their upright position after
stress from human impact over the long term.

SUMMARY OF THE INVENTION

[0006]An artificial turf has according to the invention a base layer, and
a multiplicity of blades fixed to and projecting upward from the base
layer, each of the blades are formed of an elongated plastic filament
having a longitudinally extending inner part of plastic and a
longitudinally extending outer part bonded to the inner part and of a
plastic different from the inner-part plastic.

[0007]According to the invention at least one of the two parts extends the
entire length of the blade. It is also within the scope of the invention
for an intermediate plastic part to form part of the cross section of a
blade and to extend at least essentially a fully length of the blade and
for the intermediate plastic part to be between the outer and inner
plastic parts. Preferably, the intermediate plastic part separates the
outer plastic part from the inner plastic part in the multicomponent
filament at least partially and preferably completely. The three parts
are normally formed by coextrusion.

[0008]According to a particularly preferred embodiment of the invention,
the multicomponent filaments for the blades are three-part coaxial
filaments made of the outer, inner, and intermediate plastic parts. It is
useful for the intermediate plastic part to act as a bonding agent
between the outer plastic part and the inner plastic part. Thus the
multicomponent filaments have a core-sheath structure, with the outer
plastic part forming the sheath and the inner plastic part forming the
core of the multicomponent filament. It is useful for the intermediate
plastic part to be arranged between the sheath (outer plastic part) and
the core (inner plastic part) and it is recommend for it to surround the
core at least partially, preferably completely. This means that, due to
the intermediate plastic part, there is no direct contact between the
core and the sheath.

[0009]It is within the scope of the invention for the multicomponent
filaments according to the invention to be spun from a spinning nozzle.
The individual plastics are supplied to the spinning nozzle by extruders.
After the multicomponent filaments have been spun, after the filaments
have cooled, and, optionally, after further treatment, the multicomponent
filaments are cut into appropriate lengths for the blades according to
the invention. Preferably, after spinning of the multicomponent filaments
from the spinning nozzle, they are first cooled, preferably in a water
bath. According to recommended variant embodiments, the filaments are
then stretched, in particular mechanically, and subsequently the
filaments are fixed. It then lies within the scope of the invention for
the filaments to be cut into the blade lengths. According to a
recommended variant embodiment, the filaments or monofilaments are first
attached to the base layer by tufting and subsequently trimmed to a
uniform length from the base.

[0010]According to a particularly preferred embodiment of the invention,
the one of the plastic parts is a polyolefin, preferably a polyethylene.
According to a very recommended embodiment of the invention, the
polyolefin, preferably polyethylene, forms the sheath part of the
multicomponent filament in the core-sheath structure. According to a
preferred variant embodiment of the invention, LLDPE (linear low-density
polyethylene) is used as the polyethylene. This polyethylene has proven
itself particularly well in the context of the invention. The polyolefin,
preferably polyethylene, particularly preferably LLDPE, may in particular
contain additives with UV-reflecting properties and/or additives with
antibacterial properties and/or additives in the form of fungicides.

[0011]According to a particularly preferred embodiment of the invention,
the inner plastic part is a polyamide or a polyester. Polybutylene
terephthalate (PBT) may preferably be used as the polyester. According to
a particularly preferred embodiment of the invention, however, the inner
plastic part is a polyamide. It is useful for the polyamide to form the
core of the multicomponent filament in the core-sheath structure. One
recommended variant embodiment of the invention is characterized in that
the inner plastic part is a polyamide from the group Nylon 6, Nylon 6.6,
Nylon 6.12, Nylon 6.10. Here, the use of Nylon 6 as the inner plastic
part is particularly preferred, preferably as the core part of the
multicomponent filaments in the core-sheath structure.

[0012]In accordance with the invention the intermediate plastic part is a
plastic that acts as a bonding agent between the outer plastic part,
preferably the sheath part, and the inner plastic part, preferably the
core part. In principle, the skilled practitioner is aware of plastics
that are able to act as a bonding agent, in particular between a
polyolefin and a polyamide. According to a preferred embodiment of the
invention, the intermediate plastic part is a polyamide-polyethylene
copolymer. According to another preferred variant embodiment, a
polyolefin that has been modified using a maleic acid derivative,
usefully maleic anhydride, is used as the intermediate plastic part. The
modified polyolefin is preferably a modified polyethylene or
polypropylene.

[0013]According to a recommended embodiment of the invention, the
multicomponent filaments, relative to their cross section or the surface
area of their cross section, have 5 to 50%, preferably 10 to 45%, and
most preferably 10 to 40% formed by the outer plastic part. These
percentages are percentages of surface area occupied by the outer plastic
part relative to the area of the overall cross section of the
multicomponent filament forming the blade. Preferably the outer plastic
part mentioned above is the sheath part of the multicomponent filament in
the core-sheath structure, which is preferably composed of polyethylene,
particularly preferably of LLDPE. According to a recommended embodiment,
the multicomponent filaments, relative to their cross section or the
surface area of their cross section, have of 3 to 20%, preferably 5 to
20%, and most preferably 5 to 15% formed by the intermediate plastic
part. The intermediate plastic part is preferably arranged between the
sheath part (outer plastic part) and the core part (inner plastic part)
of a multicomponent filament in the core-sheath structure. It is useful
for the intermediate plastic part in this core-sheath structure to form
the inner sheath, as it were, between the outer sheath (outer plastic
part) and the core (inner plastic part). According to a very preferred
embodiment of the invention, the multicomponent filaments, relative to
their cross section or the surface area of their cross section, have 30
to 93%, preferably 30 to 85%, and most preferably 35 to 80% formed by the
inner or core plastic part. The inner plastic part can be the primary
part of the multicomponent filaments, occupying preferably more than 40%,
most preferably more than 45%, of the area of the cross section relative
to the overall cross-sectional area of blade. Preferably, the inner
plastic part mentioned above is the core part of the multicomponent
filament in the core-sheath structure, which is preferably composed of
polyamide, very preferably of Nylon 6.

[0014]A preferred embodiment of the invention is characterized in that the
core of the multicomponent filaments in the core-sheath structure has
hollow chambers, formed as longitudinally extending voids in the core.
The use of multicomponent filaments with hollow chambers of this type in
the core has proven itself particularly well. The hollow chambers allow
an advantageous absorption of water in the multicomponent filaments
and/or in the blades of the artificial turf.

[0015]The invention is based on the realization that the artificial turf
according to the invention surprisingly fulfills all of the desired
requirements. First, the artificial turf according to the invention is
distinguished by an excellent gentleness to skin. If, for example,
athletes, fall or slip on this artificial turf, no appreciable injuries
or skin burns will result. Moreover, the artificial turf according to the
invention is distinguished by the ability of its blades to maintain their
upright position over the long term. Even in the case of frequent human
stress or impact on the blades, they still always return to their
original position. Moreover, the artificial turf according to the
invention is also distinguished by its good cushioning properties. It
should be emphasized that the artificial turf according to the invention
is relatively simple and cost-effective to produce. The artificial turf
according to the invention is also excellent for landscape gardening.

BRIEF DESCRIPTION OF THE DRAWING

[0016]The above and other objects, features, and advantages will become
more readily apparent from the following description, reference being
made to the accompanying drawing in which:

[0017]FIG. 1 is a perspective view of a piece of artificial turf according
to the invention;

[0018]FIG. 2 is a large-scale vertical section through the inventive
artificial turf; and

[0019]FIG. 3 is a longitudinal section through the multicomponent filament
forming the turf blades.

SPECIFIC DESCRIPTION

[0020]As seen in FIG. 1, artificial turf in accordance with the invention
consists of a plurality of blades 1 fixed on a base layer 2. The blades 1
are formed by a multicomponent monofilament or pieces thereof and are
advantageously fixed on the base layer 2 by tufting.

[0021]FIG. 2 shows the artificial turf in greater detail. Here, the blades
1 are shown projecting through the base layer 2 and joined together
underneath it, with their free ends projecting upward from it. The base
layer 2 is in particular a woven, knitted, or felted fabric or plastic
textile consisting preferably of a polyolefin, preferably polypropylene
or polyethylene. A layer of infill formed of multicomponent fibers and
situated between the blades 1 and on the base layer 2 is indicated
schematically at 3.

[0022]FIG. 3 shows a cross section through one of the blades 1 of a
multicomponent filament according to the invention. Here, the blade 1 or
multicomponent filament is embodied according to a preferred embodiment
of the invention with a core-sheath structure. In the illustrated
embodiment, an outer layer, tube, or sheath 4 is composed of
polyethylene, preferable LLDPE. An inner layer or core 5 in the
illustrated embodiment is composed polyamide, very preferably Nylon 6.
Between the sheath 4 and the core 5 is an intermediate layer 6 composed
of a third plastic part that is preferably composed of a
polyamide-polyethylene copolymer. This part 6 is an inner tube or sheath
that completely surrounds the core 5 and functions as a bonding agent
between the sheath 4 and the core 5. FIG. 3 shows longitudinally
extending voids or hollow chambers 7 in the core 5 to allow for
absorption of water into the blade 1. FIG. 3 also shows that the inner or
core part (polyamide or Nylon 6 in the illustrated embodiment) forms the
primary part of the multicomponent filament and represents preferably at
least 35%, most preferably at least 40% of the surface area of the cross
section relative to the area of the overall cross section of the
respective blade 7.